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Hypothermia can be induced in humans and some animals for the purpose of protecting various organs and tissues (e.g., hear, brain, kidneys) against the effects of ischemic, anoxic or toxic insult. For example, animal studies and/or clinical trials suggest that mild hypothermia can have neuroprotective and/or cardioprotective effects in animals or humans who suffer from ischemic cardiac events (e.g., myocardial infract, acute coronary syndromes, etc.), postanoxic coma after cardiopulmonary resuscitation, traumatic brain injury, stroke, subarachnoid hemorrhage, fever and neurological injury. Also, studies have shown that whole body hypothermia can ameliorate the toxic effects of radiographic contrast media on the kidneys (e.g., radiocontrast nephropathy) of patients with pre-existing renal impairment who undergo angiography procedures.
One method for inducing hypothermia is by endovascular temperature management (ETM) wherein a heat exchange catheter is inserted into a blood vessel and a thermal exchange fluid is then circulated through the heat exchange catheter. This technique can effectively cool blood flowing through the subject's vasculature and, as a result, lower the core body temperature of the subject to some desired target temperature. ETM is also capable of warming the body and/or of controlling body temperature to maintain a monitored body temperature at some selected temperature. If a controlled rate of re-warming or re-cooling from the selected target temperature is desired, that too can be accomplished by carefully controlling the amount of heat added or removed from the body and thereby controlling the temperature change of the patient.
A number of heat exchange catheters are currently available for use in ETM. One such catheter, the SoIex™ Catheter available from ZOLL Circulation, Inc. of Sunnyvale, Calif., generally comprises a flexible catheter shaft having curved loops of tubing protruding from opposite sides of a distal portion of the catheter. In operation, the distal portion of the Solex™ catheter is inserted into the vasculature of a subject and a heated or cooled thermal exchange medium is then circulated through the curved loops of tubing. This results in exchange of heat between the circulating thermal exchange medium and blood flowing through the subject's vasculature, without causing the thermal exchange medium to be infused into the subject's bloodstream.
The current Solex™ catheter is formed of two subassemblies, a proximal portion and a distal portion. The proximal portion is a dual lumen tube that has an inflow lumen through which the thermal exchange fluid flows in the distal direction and an outflow lumen through which the thermal exchange fluid flows in the proximal direction. The distal portion is a coiled shaft with thin walled tubing “sewn” onto it to form the protruding curved loops of tubing. These proximal and distal portions are then joined together to make the final catheter. This two-piece construction requires a jointure or connection midway along the catheter shaft and is relatively labor intensive.
Additionally, the coiled shaft on the distal portion of the Solex™ catheter gives rise to a “bumpy” feel as the catheter is withdrawn through a vascular introducer, such as during removal of the catheter from the subject's body. The elimination of the coiled distal shaft in favor of a smoother one-piece shaft could lessen or eliminate such “bumpy” feel as the catheter is being removed from the patient.
Accordingly, there exists a need in the art for the development of new methods for catheter manufacture that may be used for the manufacture of the Solex™ catheter and/or other catheters having similar construction, thereby eliminating the need for formation of a jointure or connection midway along the catheter shaft and potentially offering other advantages, such as; 1) reducing the number of parts used in manufacturing the catheter and/or 2) reducing the labor and manual endeavor required for manufacture of the catheter, such as eliminating the need for the delicate sewing step to attach the thin-walled tubing to the coiled shaft and/or 3) reducing or eliminating the “bumpy” feel that the catheter has when being removed from the patient.